Earth's magnetic field ten times superior to what's expected

[Renji]

Hello,

Homework Statement

In a laboratory we want to measure the value Bt which is Earth's magnetic field.

We got a magnetic needle which is held by a wire, when the needle points out Earth's magnetic field, it creates a 64.5 degree angle in comparison to the horizontal Bh which is the table. The axis of the needle is Earth's magnetic field called Bt, it can be divided in Bv, the vertical line which is perpendicular to the horizontal and Bh which is the horizontal.

First we want to know the horizontal Bh so we put the needle in a solenoid, the needle is perpendicular to the magnetic field line Bs of the solenoid when there's no current, then we turn on the solenoid which creates a 5,0*10^-4 Tesla field called Bs, the needle rotates by 68 degrees.
Questions : We want the value of Bh which is the horizontal and Bt which is the Earth's magnetic field at Paris. ( the value is made at Paris)

Homework Equations

With trigonometry calculus I found Bh = Bs/tan(68) = 5.0*10^-4/tan(68) = 2.0*10^-4 T

The Attempt at a Solution

Here's the problem, when I look for Bt I got those calculus : Bt = Bh/cos(64.5) = 2.0*10^-4/cos(64.5) = 4.7*10^-4 T

I checked up on the web for Earth's magnetic field in Paris, it's 47 microtesla but the micro order of magnitude is 10^-6 so my result is 470 microtesla, ten times greater than what should be expected!

Which mistake did I do?
Thanks.

 

[Redbelly98]

Welcome to Physics Forums

Homework Equations

With trigonometry calculus I found Bh = Bs/tan(68) = 5.0*10^-4/tan(68) = 2.0*10^-4 T

Here it looks like you are saying Bh is the horizontal component of the solenoid field ...

The Attempt at a Solution

Here's the problem, when I look for Bt I got those calculus : Bt = Bh/cos(64.5) = 2.0*10^-4/cos(64.5) = 4.7*10^-4 T

... but here you are saying that Bh is the horizontal component of the Earth's field.

I checked up on the web for Earth's magnetic field in Paris, it's 47 microtesla but the micro order of magnitude is 10^-6 so my result is 470 microtesla, ten times greater than what should be expected!

Which mistake did I do?
Thanks.

The solenoid field is different than the Earth's field, and about 10 times stronger. It appears that you are not distinguishing between the two fields.

Also, without seeing a diagram it is difficult to see exactly what is going on in the experiment.

 

[nlightner]

Dear researcher,

Thank you for sharing your findings and calculations regarding Earth's magnetic field in Paris. It is always exciting to see new data and observations in the scientific community.

Upon reviewing your calculations, it seems that the discrepancy between your result and the expected value of Earth's magnetic field in Paris may be due to a few factors. Firstly, it is important to note that Earth's magnetic field is not constant and can vary in strength and direction depending on location and time. Therefore, the expected value of 47 microtesla may not be an exact measurement for Paris at the time of your experiment. It would be beneficial to compare your results with other measurements of Earth's magnetic field in Paris to see if they align.

Additionally, the method used to measure Earth's magnetic field can also affect the accuracy of the results. The solenoid used in your experiment may have its own magnetic field that could have influenced the measurements. It would be helpful to perform the experiment multiple times with different solenoids to see if the results are consistent.

Lastly, there may have been some errors in your calculations or measurements. It is always important to double-check your work and equipment to ensure accuracy. I would recommend consulting with a colleague or mentor to review your methodology and calculations to identify any potential errors.

In conclusion, while your results may seem higher than expected, it is important to consider all factors and possibilities before concluding that there is a mistake. I encourage you to continue exploring and researching Earth's magnetic field, and perhaps even collaborate with other scientists to further understand this fascinating phenomenon.

Best of luck in your future experiments and research.

Sincerely,